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[BrantV]

Quote:

Originally posted by tomstork
1) the idea that an object made with more of a material isn't any stronger than an object with less of it is just silly. That's why you use bigger structural girders when making a bigger building. Or, for that matter, why it's safe to jump on 8" thick ice on a lake, but not on 1" thick ice.

Well in some cases, astonishing things really do happen. In the case of forged vs. cast with aluminium and many other metals, lighter forged parts are in many cases actually stronger than cast parts.

When the material is forged, it results in a better alignment in the crystalline structure. The actual atoms, are packed more efficiently, and the chemical bonds between the individual atoms become stronger. Casting on the other hand can result in bubbles. Aluminum has always been a difficult metal to cast without introduction of gaseous contaminants. Ironically enough, after decades of trying to solve the problem, there's now a huge growth in R&D trying to do just the opposite with aluminium foam.

Have you ever noticed how brittle cast iron is? It's the reason, column, girders, plates, and the connecting bolts are made from pressed materials and not cast iron.

Depending on the material, forging also gives it other attractive properties. It makes the metal more malleable and allows it to better withstand shock.